1. Field of the Invention
The present invention relates to a process for preparing an unsaturated alcohol, preferably to a process to efficiently prepare an unsaturated alcohol by selectively reducing the aldehyde group of an .alpha.,.beta.-unsaturated aldehyde compound.
2. Description of Related Art
For preparing the unsaturated alcohols, a process is known, wherein the aldehyde group of an .alpha.,.beta.-unsaturated aldehyde compound is selectively reduced. Particularly, an unsaturated alcohol having 2,2,3-trimethyl-3-cyclopenten-1-yl group represented by the formula (I): ##STR2## is known to be a perfume having musk-like smell as well as sandalwood-like smell, and prepared by selectively reducing the aldehyde group alone of an .alpha.,.beta.-unsaturated aldehyde compound having 2,2,3-trimethyl-3-cyclopenten-1-yl group represented by the above formula (I).
For example, JP-B 56-36176 discloses a process for preparing 2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-buten-1-ol represented by the formula (III'): ##STR3## by selectively reducing the aldehyde group alone of 2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-buten-1-al represented by the formula (II'): ##STR4## using aluminum alcoholate or a metal hydride compound in the presence of isopropyl alcohol.
This method, however, utilizes a large amount of aluminum alcoholate or a metal hydride compound as much as 40 mol % of the aldehyde as the starting material, as well as a large excess of isopropyl alcohol, i.e., more than 20 times by mole the amount of the aldehyde as the starting material, that is, this method is not efficient with low productivity.